The invention relates to a doctor apparatus in connection with a roll or a cylinder in a paper or board machine.
The invention relates to a doctor apparatus in connection with a roll or a cylinder in a paper or board machine.
The large structural dimensions of doctor beams and the fact that doctor beams become heavy pose a problem in the arrangements of prior art. This means, for instance, that it is almost impossible to produce an oscillation movement for a doctor beam. Large dimensions and heavy beams have led to the fact that construction of doctor beams has thus become a costly working step. The cost of material alone has been high. In this application, attempts have been made to form a totally novel type of doctor beam by means of which the big problems arising from heavy doctor beams in the prior art structures are avoided. In the invention, a doctor beam structure has been formed in which it has been possible to form the doctor beam, being advantageously made of a composite material, into a lightweight rib-like part, and into which doctor beam it has already in itself been possible to form blade holder structures, i.e. the doctor beam itself constitutes a blade holder. In accordance with the invention, the bearing arrangement of the doctor beam is accomplished such that the doctor beam can be both oscillated and pivoted by means of loading hoses. A pneumatic cylinder is advantageously used as an oscillation actuator, in which connection counterforce and counter-motion are produced by means of a spring fixed between the doctor beam and a frame.